ATLANTA, Sept. 29 (UPI) -- Meriwether Lewis and William Clark's hugely successful 1804-1806 expedition across North America benefited from unusually favorable climate conditions.
Georgia State University geographer Paul A. Knapp concludes the explorers happened upon a narrow "window of opportunity" between severe droughts that facilitated their fascinating reports of lush landscapes and dense wildlife, ABC News reported.
Lewis and Clark "traveled through the American Northwest during a climatically favorable period after one of the most severe droughts within the past several centuries, and they concluded their travel two years before the onset of another major drought," Knapp wrote in his report, which appears in the current Bulletin of the American Meteorological Society.
